Btrfs: Use a chunk of the key flags to record the item type.

Add (untested and simple) directory item code
Fix comp_keys to use the new key ordering
Add btrfs_insert_empty_item

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/dir-item.c

@@ -0,0 +1,102 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "kerncompat.h"
+#include "radix-tree.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "hash.h"
+
+int btrfs_insert_dir_item(struct btrfs_root *root, char *name, int name_len,
+			  u64 dir, u64 objectid, u8 type)
+{
+	int ret = 0;
+	struct btrfs_path path;
+	struct btrfs_dir_item *dir_item;
+	char *name_ptr;
+	struct btrfs_key key;
+	u32 data_size;
+
+	key.objectid = dir;
+	key.flags = 0;
+	ret = btrfs_name_hash(name, name_len, &key.offset);
+	BUG_ON(ret);
+	btrfs_init_path(&path);
+	data_size = sizeof(*dir_item) + name_len;
+	ret = btrfs_insert_empty_item(root, &path, &key, data_size);
+	if (ret)
+		goto out;
+
+	dir_item = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0],
+				  struct btrfs_dir_item);
+	btrfs_set_dir_objectid(dir_item, objectid);
+	btrfs_set_dir_type(dir_item, type);
+	btrfs_set_dir_flags(dir_item, 0);
+	name_ptr = (char *)(dir_item + 1);
+	memcpy(name_ptr, name, name_len);
+out:
+	btrfs_release_path(root, &path);
+	return ret;
+}
+
+int btrfs_del_dir_item(struct btrfs_root *root, u64 dir, char *name,
+		       int name_len)
+{
+	int ret = 0;
+	struct btrfs_path path;
+	struct btrfs_key key;
+
+	key.objectid = dir;
+	key.flags = 0;
+	ret = btrfs_name_hash(name, name_len, &key.offset);
+	BUG_ON(ret);
+	btrfs_init_path(&path);
+	ret = btrfs_search_slot(root, &key, &path, 0, 1);
+	if (ret)
+		goto out;
+	ret = btrfs_del_item(root, &path);
+out:
+	btrfs_release_path(root, &path);
+	return ret;
+}
+
+int btrfs_lookup_dir_item(struct btrfs_root *root, u64 dir, char *name,
+			  int name_len, u64 *objectid)
+{
+	int ret = 0;
+	struct btrfs_path path;
+	struct btrfs_dir_item *dir_item;
+	char *name_ptr;
+	struct btrfs_key key;
+	u32 item_len;
+	struct btrfs_item *item;
+
+	key.objectid = dir;
+	key.flags = 0;
+	ret = btrfs_name_hash(name, name_len, &key.offset);
+	BUG_ON(ret);
+	btrfs_init_path(&path);
+	ret = btrfs_search_slot(root, &key, &path, 0, 0);
+	if (ret)
+		goto out;
+
+	dir_item = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0],
+				  struct btrfs_dir_item);
+
+	item = path.nodes[0]->leaf.items + path.slots[0];
+	item_len = btrfs_item_size(item);
+	if (item_len != name_len + sizeof(struct btrfs_dir_item)) {
+		BUG();
+		ret = 1;
+		goto out;
+	}
+	name_ptr = (char *)(dir_item + 1);
+	if (memcmp(name_ptr, name, name_len)) {
+		BUG();
+		ret = 1;
+		goto out;
+	}
+	*objectid = btrfs_dir_objectid(dir_item);
+out:
+	btrfs_release_path(root, &path);
+	return ret;
+}